1. Field of the Invention
The present invention relates to a circuit breaker, and more particularly, to a circuit breaker which can open and close a line by a driving force obtained by a spring and a linkage.
2. Background of the Invention
In general, a circuit breaker is an electrical device that protects circuits and load devices by automatically closing a line in the event of an abnormal current.
FIG. 1 is a cross-sectional view showing a conventional circuit breaker in a manual OFF position.
As shown in FIG. 1, the conventional circuit breaker includes a fixed contact FC within a case C, a moving contact OC rotatably mounted on the case C at one end to be brought into contact with or separated from the fixed contact FC, and a switching mechanism that generates a driving force to rotate the moving contact OC.
The fixed contact FC includes a fixed point of contact FCP on one side.
The moving contact OC includes a moving point of contact OCP on one side.
The switching mechanism includes a linkage, a handle 10 spaced away from the linkage, a tension spring S connecting the linkage and the handle 10, a transfer link 90 that transfer a driving force from the linkage to the moving contact OC.
The linkage includes a trip latch 20 for performing a tripping operation, a first rocker 40 hinged to the trip latch 20, a second rocker 80 hinged to the case C, and a connecting link 60 connecting the first rocker 40 and the second rocker 80.
One end of the trip latch 20 is hinged to the case C, and the other end thereof is held by a latch holder 28.
The trip latch 20 includes a latch hinge hole 26 on one side.
One end of the first rocker 40 is hinged to the latch hinge hole 26 by a first rotation axis 30.
As such, the first rocker 40 is rotatably mounted on the first rotation axis 30.
The second rocker 80 is spaced away from the first rocker 40.
More specifically, one end of the second rocker 80 is hinged to the case C by a second rotation axis 82.
As such, the second rocker 80 is rotatably mounted on the second rotation axis.
Moreover, the second rocker 80 includes a primary second rocker hinge hole 84 and a secondary second rocker hinge hole (not shown).
One end of the connecting link 60 is hinged to the other end of the first rocker 40 by a first pin 50, and the other end thereof is hinged to the primary second rocker hinge hole 84 by a second pin 70.
The first pin 50 includes a first spring fastener 52 for supporting one end of the tension spring S.
One end of the handle 10 is hinged to the case C, and the other end thereof protrudes from the case C.
A second spring fastener 16 for supporting the other end of the tension spring S is provided on one side of the handle 10.
One end of the tension spring S is supported on the first spring 52, and the other end thereof is supported on the second spring fastener 16.
As such, the tension spring S generates a driving force on the first pin 50.
One end of the transfer link 90 is hinged to the secondary second rocker hinge hole (not shown) by a third pin 92, and the other end thereof is hinged to a moving contact hinge hole (not shown) by a fourth pin 94.
With this configuration, the conventional circuit breaker in the manual OFF position is put into the ON position as the handle 10 rotates counterclockwise as shown in the drawing.
The tension spring S rotates counterclockwise as shown in the drawing on the first spring fastener 52 by the rotation of the handle.
The first rocker 40 rotates clockwise as shown in the drawing around the first rotation axis 30 by means of the tension spring S.
Accordingly, the connecting link 60 rotates and moves counterclockwise as shown in the drawing by means of the first rocker 40 and the first pin 50.
The second rocker 80 rotates clockwise as shown in the drawing around the second rotation axis 82 by means of the connecting link 60.
Accordingly, the third pin 92 moves clockwise as shown in the drawing along the circumference around the second rotation axis 82.
The transfer link 90 rotates and moves counterclockwise as shown in the drawing by means of the second rocker 80 and the third pin 92.
The moving contact OC rotates counterclockwise as shown in the drawing around a moving contact rotation axis OCA by means of the transfer link 90.
As such, the moving point of contact OCP is brought into contact with the fixed point of contact FCP.
That is, the circuit breaker is put into the ON position.
By the way, if the conventional circuit breaker requires an increased number of moving contacts OC and increased input load for a change in perturbation structure, it is necessary to increase the load on the tension spring S or change the link structure and link ratio of the switching mechanism.
However, increasing the load on the tension spring S leads to the problem of increased load for all operations except the ON operation.
Meanwhile, changing the link structure and link ratio of the switching mechanism may give unnecessary effects (e.g., increasing the user operability for a reset operation) on operations other than the ON operation. Also, since a breaker and a switching mechanism cannot be used together if they are of different types, the switching mechanism as well needs to be modified in order to dualize the switching mechanism or use it together with the breaker.